U.S. patent number 9,821,395 [Application Number 14/741,597] was granted by the patent office on 2017-11-21 for method for producing a pin for a feedthrough of an electromedical implant and a feedthrough.
This patent grant is currently assigned to BIOTRONIK SE & Co. KG. The grantee listed for this patent is BIOTRONIK SE & Co. KG. Invention is credited to Michael Arnold, Daniel Kronmueller, Peter Meidlein, Josef Teske.
United States Patent |
9,821,395 |
Kronmueller , et
al. |
November 21, 2017 |
Method for producing a pin for a feedthrough of an electromedical
implant and a feedthrough
Abstract
A method for producing a pin for a feedthrough for an
electromedical implant. A pin is produced using the following
method steps: creating a foil-, sheet- or strip-shaped
semi-finished product by joining at least one first layer element
including an electrically conducting, preferably biocompatible,
material in foil, sheet or strip form and at least one second layer
element including a solder and/or an easily soft-solderable
material, preferably in wire, sheet or strip form, or by applying
the at least one second layer element onto the at least one first
layer element; and at least partially detaching a pin, or a set of
multiple pins connected to a connecting web 46, from the
semi-finished product. A method is also provided for producing a
feedthrough and an electromedical implant and to a pin, a
feedthrough or an implant produced in the corresponding manner.
Inventors: |
Kronmueller; Daniel (Nuremberg,
DE), Arnold; Michael (Erlangen, DE), Teske;
Josef (Hallstadt, DE), Meidlein; Peter
(Nuremberg, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
BIOTRONIK SE & Co. KG |
Berlin |
N/A |
DE |
|
|
Assignee: |
BIOTRONIK SE & Co. KG
(Berlin, DE)
|
Family
ID: |
53510612 |
Appl.
No.: |
14/741,597 |
Filed: |
June 17, 2015 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20160001387 A1 |
Jan 7, 2016 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62021212 |
Jul 7, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C25D
7/0614 (20130101); B23K 31/02 (20130101); B23K
1/0008 (20130101); A61N 1/3754 (20130101) |
Current International
Class: |
B23K
37/00 (20060101); B23K 1/00 (20060101); B23K
31/02 (20060101); C25D 7/06 (20060101); A61N
1/375 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2 371 418 |
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Oct 2011 |
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EP |
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2 529 790 |
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Dec 2012 |
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EP |
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863386 |
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Mar 1961 |
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GB |
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Other References
European Search Report and Annex to the European Search Report on
European Patent Application No. EP 15 17 3082, dated Nov. 5, 2015
(7 pages). cited by applicant.
|
Primary Examiner: Arbes; Carl
Attorney, Agent or Firm: Buchanan Ingersoll & Rooney
PC
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This patent application claims the benefit of U.S. Provisional
Patent Application No. 62/021,212, filed on Jul. 7, 2014, which is
hereby incorporated by reference in its entirety.
Claims
We claim:
1. A method for producing a pin, or a set of multiple pins for a
feedthrough for an electromedical implant, the method comprising
the following steps: creating a sheet- or strip-shaped
semi-finished product by joining at least one first layer element
comprising an electrically conducting and biocompatible material in
sheet or strip form and at least one second layer element
comprising an easily soft-solderable material in sheet or strip
form; applying at least one solder inhibitor layer element in sheet
or strip form to the semi-finished product and optionally joining
the at least one solder inhibitor layer element thereto; and at
least partially detaching a pin, or a set of multiple pins
connected to a connecting web, from the semi-finished product.
2. The method according to claim 1, wherein the at least one solder
inhibitor layer element in sheet or strip form is joined to the
semi-finished product.
3. The method according to claim 1, wherein the semi-finished
product additionally comprises at least one third layer element
including an insulator or a ductile metal, which is joined with the
at least one first layer element.
4. The method according to claim 1, wherein a top coat is applied
to the semi-finished product by way of an electroplating bath,
prior to the at least partial detachment of the pin, or of the set
of multiple pins, from the semi-finished product.
5. The method according to claim 4, wherein the top coat is applied
to at least a portion of the at least one second layer element.
6. The method according to claim 1, wherein the pin, or at least
one pin of the set of multiple pins, is formed prior to or after
being at least partially detached from the semi-finished product in
such a way that the at least one second layer at least partially
surrounds the pin.
7. The method according to claim 6, wherein the pin, or each pin of
the set of multiple pins, is formed after the at least partial
detachment in such a way that at least one circumferential
protrusion is created, the protrusion being located in each case on
the side surface of the particular pin.
8. The method according to claim 3, wherein the at least partial
detachment takes place in a direction that is substantially
perpendicular to the direction of joining of the at least one first
layer element with the at least one second element.
9. The method according to claim 1, wherein a section of the pin is
turned into a round shape by way of forming after the at least
partial detachment.
10. The method according to claim 1, wherein the pin is formed on
at least one end section into a gull wing, J-lead or SOP-like shape
after the at least partial detachment.
11. The method according to claim 1, wherein a predetermined
breaking point is introduced into an end section of a pin of the
set of multiple pins connected to a connecting web.
12. A method for producing a feedthrough for an electromedical
implant, wherein a body of a feedthrough having at least one
continuous cut-out is provided, comprising producing a pin in
according to claim 1, and carrying out an additional step,
according to which the pin, or each pin of the set of multiple
pins, is subsequently connected to the inner surface of a
continuous cut-out of the insulator by way of brazing.
13. The method according to claim 12, wherein the multiple pins are
subsequently detached from each other.
14. A method for producing an electromedical implant comprising a
printed circuit board, comprising producing a feedthrough according
to claim 12, and wherein subsequently each pin of the feedthrough
is connected to a terminal of the printed circuit board by way of
brazing or welding.
15. A pin for an electromedical implant, produced using the method
according to claim 1.
16. A feedthrough for an electromedical implant, produced using the
method according to claim 12.
17. An electromedical implant, produced using the method according
to claim 14.
18. The method according to claim 1, wherein the semi-finished
product additionally comprises at least one third layer element
including an insulator or a ductile metal, which is joined with the
at least one second layer element.
19. The method according to claim 1, wherein a top coat is applied
to the semi-finished product by way of an electroplating bath,
after the at least partial detachment of the pin, or of the set of
multiple pins, from the semi-finished product.
20. The method according to claim 6, wherein the pin, or each pin
of the set of multiple pins, is formed after the at least partial
detachment in such a way that at least one circumferential recess
is created, the recess being located in each case on the side
surface of the particular pin.
21. The method according to claim 3, wherein the at least partial
detachment takes place in a direction that is substantially
perpendicular to the direction of joining of the at least one third
layer element.
22. A method for producing a pin, or a set of multiple pins for a
feedthrough for an electromedical implant, the method comprising
the following steps: creating a sheet or strip shaped semi-finished
product by applying at least one second layer element comprising an
easily soft solderable material in sheet or strip form, onto at
least one first layer element comprising an electrically conducting
and biocompatible material in sheet or strip form; applying at
least one solder inhibitor layer element in sheet or strip form to
the semi-finished product and optionally joining the at least one
solder inhibitor layer element thereto; and at least partially
detaching a pin, or a set of multiple pins connected to a
connecting web, from the semi-finished product.
23. A method for producing a pin, or a set of multiple pins for a
feedthrough for an electromedical implant, the method comprising
the following steps: creating a sheet or strip shaped semi-finished
product by joining at least one first layer element comprising an
electrically conducting and biocompatible material in sheet or
strip form and at least one second layer element comprising a
solder material in sheet or strip form; applying at least one
solder inhibitor layer element in sheet or strip form to the
semi-finished product and optionally joining the at least one
solder inhibitor layer element thereto; and at least partially
detaching a pin, or a set of multiple pins connected to a
connecting web, from the semi-finished product.
24. A method for producing a pin, or a set of multiple pins for a
feedthrough for an electromedical implant, the method comprising
the following steps: creating a sheet or strip shaped semi-finished
product by applying at least one second layer element comprising a
solder material in sheet or strip form, onto at least one first
layer element comprising an electrically conducting and
biocompatible material in sheet or strip form; at least one solder
inhibitor layer element in sheet or strip form is applied to the
semi-finished product and optionally joined thereto; and at least
partially detaching a pin, or a set of multiple pins connected to a
connecting web, from the semi-finished product.
Description
TECHNICAL FIELD
The present invention relates to a method for producing a pin for
an electromedical implant, to a method for producing a feedthrough
and an electromedical implant, and to a pin produced in the
corresponding manner, to a feedthrough produced in the
corresponding manner, and to an implant.
BACKGROUND
Medical or active implants are known from the state of the art in
great diversity. In the context of the present invention, an
electromedical implant shall be understood to mean an implant that
comprises a power supply unit (such as, for example, a battery) and
electrical and/or electronic components such as, for example, a
printed circuit board, which are disposed in a housing that is
hermetically sealed. Such electromedical implants are, for example,
cardiac pacemakers, defibrillators, neurostimulators, leadless
pacemakers, cardioverters, drug pump implants, cochlear implants or
other hermetically encapsulated electronic products for
implantation in a human or an animal body.
Such implants are frequently connected to electrode lead wires,
which after implantation in a human or an animal body treat the
same, for example, by transmitting and/or delivering stimulation
pulses and/or defibrillator shocks to certain sites of the body, or
which are used to detect electrical potential of and from sites of
the body. For this purpose, an electrical connection must be
established between the electrical and/or electronic components
disposed in the housing interior and the respective electrode lead
wire. This electrical connection is generally implemented by way of
a feedthrough and/or what is known as a header. Such a feedthrough
ensures at least one electrical connection between the interior of
the housing and the exterior, while also hermetically sealing the
housing of the implant. The header, attached via the feedthrough,
continues the electrical connection of the feedthrough to a contact
point and is used to plug the at least one electrode lead wire into
a corresponding, and usually standardized, socket. An electrical
contact is thus established between the implant and the connecting
piece of the electrode lead wire at the contact points of the
bushing. A feedthrough and a header can also be implemented in a
single component. In this case as well, such a combined component
is generally referred to hereafter as a feedthrough.
Such feedthroughs generally comprise an electrically insulating
body, this being the insulator, which is frequently produced from
ceramic or other similar material and implements the hermetic
sealing of the housing. The insulator often has a flange for this
purpose, by way of which the insulator is inserted into the open
end of the housing of the implant. The insulator furthermore
frequently includes continuous cut-outs, such as, for example,
boreholes, in each of which a connection pin (hereinafter
abbreviated as pin) is provided, which is also referred to as a
terminal pin. The pin is frequently attached in the cut-out, which
can additionally comprise a feedthrough sleeve, by way of
high-temperature brazing. The pin is used to establish an
electrical connection between the housing interior and the header
or the electrode lead wire. Such a feedthrough comprising a pin is
known from the published prior art European Patent Application No.
EP 2 371 418, for example, which shows and describes in particular
a feedthrough comprising a terminal pin. The pin comprises a first
section made of a biocompatible material and a second section made
of a material that can be joined using low energy. The second
section is to be disposed in the interior of the housing of the
implant.
Brazing is a known thermal process for integrally joining
materials, the process being usable to establish an electrical
connection and being carried out using a solder. Depending on the
temperature, a person skilled in the art distinguishes between
three known methods. The process is referred to as soft soldering
in the temperature range up to 450.degree. C. Known soft solders
are Sn63Pb37, Sn96Ag4 and Au80Sn20, for example. The process is
referred to as brazing in the temperature range between 450.degree.
C. and 900.degree. C. For this, silver or brass solders are
frequently used (such as, for example, L-Ag44 (Ag44Cu30Zn26)). The
process is referred to as high-temperature brazing at temperatures
above 900.degree. C. In medical technology, high-temperature
solders include Au (99.95), AuAg8, AuPt10 and Ti60Ni25Cu15, for
example.
Conventionally, the pin disposed in the feedthrough is directly
connected to a terminal of a printed circuit board by way of soft
soldering or welding so as to establish the electrical connection
with the electronic circuit located on the printed circuit board.
The published prior art European Application No. EP 2 529 790
discloses the use of a connector, which is attached to the terminal
pin by way of a clip connection. The connector moreover comprises a
sleeve, which surrounds the terminal pin and is fixed on a printed
circuit board disposed in the interior of the implant by way of
soft soldering or welding so as to establish an electrical
connection.
In the production of such feedthroughs and implants, in particular,
inserting and brazing the pin and establishing the electrical
connection between the pin and the printed circuit board are
complex and cost-intensive. The elements of a pin are initially
produced individually and then assembled and joined manually.
For example, gold solder rings or sleeves are produced separately
prior to brazing the pin to the feedthrough and are manually
assembled individually with a pin. The problem that exists with
this process is that the entire feedthrough must be removed if a
solder ring or a solder sleeve falls off during mounting. In the
case of multi-pole feedthroughs, the costs resulting from mounting
errors are therefore very high. Additionally, the problem exists
that the product groups encompassing the pin and solder arrive
individually in the receiving department of the producing company.
Until processing, these product groups must be stored separately
from other components. This likewise creates high complexity for
each component in materials management. Moreover, each component
must be independently tested for defects. The complexities for
individual processes that are related to this (stamping, cleaning,
sorting, packaging, etc.) exceed the material value of the
respective component several fold.
Using an upstream high-temperature brazing process, the solder can
be brazed onto the wire pin. However, this is a multi-stage joining
process using the individual components, in which overall no
savings are achieved in terms of labor time or cost.
Additionally, the option exists to coat the pins with solder
material by way of electroplating or by way of coating methods.
However, the galvanic coating of wire sections in the form of bulk
material is likewise very complex, since a uniform layer thickness
can only be assured by previously separating and aligning the pins.
Moreover, inclusions from the electroplating solution may occur.
Such an electroplating solution additionally often represents a
dangerous or toxic substance, which is undesirable in the field of
medical technology and may be problematic in terms of disposal.
If PVD or CVD methods are used for coating, the maximally
achievable layer thickness is limited to several 10 .mu.m due to
economic efficiency. This method likewise necessitates separation
of the pins. It may be necessary to mask the pins for the
application process, making the method not cost-efficient for the
application of a sufficient amount of solder.
The production process is also initially separate on the implant
interior at the contact point between the pin and the printed
circuit board, which is normally joined by way of a soft solder
joint using, for example, SMT methods. The required soft
solderability for the SMT process is created by adding further
components during or after the high-temperature brazing
process.
Overall, bulk material is problematic to process in production
since the respective components must be singulated, aligned and
optionally oriented prior to processing, which represents an
additional process step that is required for measuring or testing
tasks in a partially or fully automated production plant.
The present invention is directed toward overcoming one or more of
the above-mentioned problems.
SUMMARY
Therefore, it is an object of the present invention to simplify the
production of the feedthrough and of an electromedical implant and
to design the process to be more cost-effective.
At least the above object is achieved by a method for producing a
pin for the feedthrough of an electromedical implant, comprising
the following steps: creating a foil-, sheet- or strip-shaped
semi-finished product by joining at least one first layer element
comprising an electrically conducting, preferably biocompatible,
material in foil, sheet or strip form, and at least one second
layer element comprising a solder and/or a easily soft-solderable
material, preferably in wire, sheet or strip form, or by applying
the at least one second layer element onto the at least one first
layer element; and at least partially detaching a pin, or a set of
multiple pins connected to a connecting web, from the semi-finished
product.
The method according to the present invention is based on the
realization by the inventors that the production process of the pin
must be designed fundamentally differently so to achieve
simplifications and/or cost savings in the production of the
feedthrough and of the implant. The production process has now been
modified in such a way that initially the elements of the pin in
foil, sheet or strip form are joined. The pins are singulated
subsequently by detachment from the foil, the sheet or the
strip.
The advantage of the method according to the present invention is,
in particular, that bulk material processes, or individual manual
assembly processes of small parts, are avoided when the pins or pin
sets are separated later in the process chain, such as not until
after high-temperature brazing. The method according to the present
invention can additionally be used to adjust the content of the
electrically conducting material and of the high-temperature solder
or soft-solderable material within narrow limits in a targeted
manner. While the method according to the present invention
increases the use of material due to the joining process at the raw
material level, it is possible to considerably increase the quality
due to the comparatively simple and reliable joining process and
easier introduction of the pin into the feedthrough and simpler
brazing, and it is thus possible to effectively contribute to
lowering the reject rates. In the case of feedthroughs that can be
brazed using SMT (surface mounting technology) and using ten signal
pins, for example, the mounting time decreases by approximately
thirty percent per feedthrough.
Many error patterns that arise from a manual mounting process of
the individual components in relation to each other can be avoided
(such as, for example, "coaxiality", "contact element missing",
etc.). As a result, testing for such error patterns in production
becomes considerably easier.
Due to a collective separation process from previously joined
materials, it becomes easier to coordinate component tolerances of
the feedthrough components with each other during the design phase,
since some parts are already being produced at identical
tolerances.
Moreover, visual inspection and dimensional testing likewise become
easier since they can be carried out at least partially already on
the semi-finished product. In this way, previously still very
complex testing tasks that took place only sporadically can be
broken down into several independent individual inspections. By
joining the functional elements of the pin in a separate process,
the occurrence of errors in the joining process of the pin in the
feedthrough is minimized. By sorting faulty pins already after the
pins have been produced, it is possible to prevent these from being
processed into feedthroughs. This increases the economic efficiency
of the joining processes.
Overall, the procedure according to the present invention, in which
the different pin materials are already joined together in the
semi-finished product stage, combines multiple cost-intensive
individual manual processes into few, well-controllable process
steps, which can be easily automated. By redesigning the processes,
the pin can be produced cost-effectively both in the form of strip
material in average quantities and using reel-to-reel methods in
large quantities.
In a preferred exemplary embodiment, only a portion of the contour
of the pins is initially detached from the semi-finished product
(for example, cut out by way of punching) prior to fully detaching
the pin, or a set of multiple pins, from the semi-finished product
and subsequently at least a sub-region of the pin is formed (such
as, for example, by embossing, bending, etc.). In this way, the
forming process can be achieved particularly easily since the pin
is still attached to the semi-finished product. Details with regard
to the forming processes are described hereafter. The pin is fully
detached from the semi-finished product after the forming process,
such as, for example, by way of punching or along a predetermined
breaking point.
The first layer element and the second layer element are connected
to each other in a form-locked or integral manner preferably during
production of the foil-, sheet- or strip-shaped semi-finished
product. Joining may be carried out with the application of heat,
wherein inter-diffusion of the materials of the two layer elements
can be influenced by the materials that are used, the layer
geometry and the process parameters that are used (such as, for
example, diffusion heating).
As an alternative, the at least one second layer element can be
applied and integrally joined to the first layer element using a
vacuum technology coating method (PVD or CVD) or a galvanic coating
can be applied to the first layer element. Vacuum technology
coating methods generate coating thicknesses between 0.1 .mu.m and
10 .mu.m; typical layer thicknesses in the range of 0.1 .mu.m to 10
.mu.m are likewise achievable by way of electroplating:
The at least one first layer element is preferably made of a
biocompatible electrically conducting material in foil, sheet or
strip form, for example, comprising an element from the group
consisting of Nb, Pt, Pd, Ta, Zr, Ir, Ru and Hf, or an alloy
thereof, preferably the at least one first layer element comprises
PtIr10, PtRu10 and/or surgical stainless steel (such as, for
example, 316L). Moreover, the at least one first layer element can
comprise at least one element from the group consisting of Mo, Wo,
Cr, V and Al, or an alloy thereof, such as FeNi, FeNiCo, FeCr.
The at least one first layer element is preferably cleaned and
degreased prior to being joined with the at least one second layer
element. It is also preferred if the first layer element is a foil
or a sheet comprising at least one step and/or groove and/or
comprising multiple material layers (multi-layer sheet).
After the semi-finished product has been produced, it can be
measured, post-processed and optionally sorted. Moreover,
intermediate steps such as cleaning, pickling, polishing or the
like can be carried out at any time.
For example, the at least one second layer element comprises a
high-temperature solder, such as at least one element from the
group Au and Ag, or an alloy thereof (such as AuNi, AuPt10, AgCu,
AuCu) and/or an active solder (such as AuCuNi, Ti70Ni15Cu15,
Ag68Cu26Ti6, Ti67Ni33) and/or a glass solder, which is preferably
designed to be biocompatible. Suitable glass solders are glasses
having a reduced softening point and a defined composition.
The second element can comprise Cu, Ag, Au, Ni, Pd, Pt, Ir, Fe or
alloys, in particular, CuAg0.10, CuAg.10P, CuTeP, for example, as
soft-solderable materials. As an alternative, the second layer
element can be used as a layer system made of these materials.
In a preferred exemplary embodiment, essentially known methods such
as, for example, cladding, rolling, brazing or roller seam welding
can be used to join the at least one first layer element to the at
least one second layer element.
The detachment according to the present invention of a pin, or of a
set of multiple pins connected to a connecting web, from the
semi-finished product or the blank is preferably carried out by way
of fine blanking, punching, chemical milling, laser cutting or
water jet cutting. The respective method that is used depends on
the geometry and the tolerance requirements for the particular pin,
or set of multiple pins.
It is advantageous to form layers as solder inhibitor layers or
secondary layers on sub-regions or regions of the semi-finished
product.
For example, a thin layer (layer thickness at least 10 .mu.m, and
preferably at least 50 .mu.m), including at least one element from
the group consisting of Al, Mg, Ca, Zr and Y, or an alloy of these
elements, is applied to the at least one first layer element, the
thin layer preferably being applied to at least a portion of the
surface of the at least one first layer element, in addition to the
at least one second layer element comprising the solder, and
optionally being joined thereto. For this purpose, the
above-mentioned joining methods can be used. The described layers
can preferably be oxidized both selectively and in a planar manner.
Areas that are not to be coated are masked using photoresist or
paint. Masked regions remain protected from oxidation and can thus
be better wetted with solder than the oxides. Oxidation during a
wet-chemical treatment (such as cleaning of the pins) to obtain a
metal oxide layer, such as an aluminum oxide layer, an yttrium
oxide layer or a zirconium oxide layer, which assumes the function
of a solder inhibitor layer or solder barrier, is particularly
advantageous. After oxidation, the photoresist can be removed from
the component and the normal chemical treatment can be carried
out.
It is further advantageous if the semi-finished product
additionally comprises at least one third layer element including
an insulator or a ductile metal, which is joined with the at least
one first layer element and/or the at least one second layer
element. The at least one first layer element including a metallic
conductor and the at least one third layer element including an
insulator preferably form a base material, which is designed as a
multi-layer sheet. A pin comprising such a base material can be
used as a multi-pole feedthrough pin. The at least one first layer
element and/or the at least one second layer element having a wire,
sheet or strip form are joined with the at least one third layer
element in wire, sheet or strip form by way of the above-described
joining methods. The ductile material ensures better formability
during forming (such as, for example, circular embossing) and
prevents the solder of the second layer element from laterally
flowing away.
It is advantageous if the surfaces are planar, in particular in the
case of punching or embossing. For this purpose, a sacrificial
layer made of a ductile material (such as aluminum) can be applied
to the at least one first layer element, the sacrificial layer
being used to fill cavities and equalize the height between the
uppermost first layer element and the uppermost second layer
element. After forming, the sacrificial layer can be removed very
easily from the other layer elements in a cleaning process using a
lye. Preferably sodium hydroxide having a concentration of 10 to
45% at a temperature of 30 to 70.degree. C. is used.
In a further preferred exemplary embodiment, a top coat is applied
to the semi-finished product for improved soft solderability or as
a protective layer, preferably by way of an electroplating bath,
prior to and/or after the optionally at least partial detachment of
the pin, or of the set of multiple pins, from the semi-finished
product.
The top coat for improved soft solderability is preferably provided
at least partially in the region in which the at least one second
layer element comprising a soft-solderable material is disposed. In
this way, it can be ensured, for example, when using nickel as the
soft-solderable material, that no exposed nickel surfaces exist on
the pin, from which nickel can be carried over in an uncontrolled
manner during further processing steps, and that the
soft-solderable material is encapsulated by a noble metal (such as
Au). Moreover, the layer thickness can be homogenized by another
coating with the second layer element or an alloying constituent
after the process step. It can thus be ensured that the pin can be
evenly wetted from all sides, which is to say also at the edges
detached from the semi-finished product, with the soft solder when
the pin is brazed to the printed circuit board or into the cut-out
of the feedthrough. Such a top coat can be made of Au or Pd or an
alloy made of other noble metals, for example. Depending on the
material to be joined and the production process, different surface
finishing methods (such as, for example, ENIG--electroless nickel
immersion gold, ENEPIG--electroless nickel electroless palladium
immersion gold, or HAL gold--hot air leveled gold) are
possible.
A protective layer can be applied to the surface of the first
and/or second layer elements as a seal until further processing,
wherein a polymer or an organic protective film (OSP--organic
surface protection) is used for this purpose. Known protective
films can be completely or selectively deposited onto the pin after
partial or complete detachment. Typical layer thicknesses are 0.2
.mu.m to 0.6 .mu.m and include substituted imidiazoles and/or
triazoles, for example. The protective film typically prevents the
base material from oxidizing for several months during storage and
pyrolyzes immediately prior to or during the brazing or soft
soldering process. The protective film is applied to the pin
sections by way of coating (such as, for example, painting,
dipping, etc.) or using the reel-to-reel method immediately after
cleaning or pickling.
It has been found to be particularly advantageous in one exemplary
embodiment of the method according to the present invention to form
the pin prior to or after being at least partially detached from
the semi-finished product, and preferably in such a way that the at
least one second layer element at least partially surrounds the
pin. This is advantageous since a sharp separating edge is created
when detaching the pin, or of the set of multiple pins, from the
semi-finished product, and for example, the deposited solder is
not, or only partially, disposed on the cutting surface. The solder
distributes around the pin when the pin is brazed to the
feedthrough. So as to achieve a more homogeneous distribution of
the solder around the pin, it is therefore advantageous to
distribute or spread the deposited solder over all sides of the pin
by way of forming. The spreading ensures that the solder cone
around the pin closes during melting, thereby creating a reliable
connection. The likelihood of flaws in the solder is thus
minimized. The same applies analogously to the at least one second
layer element comprising a soft-solderable material.
It is further advantageous that the pin, or each pin of the set of
multiple pins, is formed after the at least partial detachment in
such a way that at least one, preferably circumferential,
protrusion and/or at least one recess are created, wherein the
protrusion and/or the recess are located in each case on the side
surface (lateral face) of the particular pin. Such a protrusion or
stop allows the pin to keep its position in the feedthrough during
the brazing process, or it allows correct positioning of the pin in
the feedthrough to be achieved. A recess can additionally serve as
a solder stop.
It is further advantageous if the at least partial detachment takes
place in a direction that is substantially perpendicular
(transverse) to the direction of joining of the at least one first
layer element with the at least one second element and/or the at
least one third layer element. In this way, for example, the
rolling direction, the cladding direction, which is to say the
joining direction of the materials, is substantially perpendicular
to the longitudinal and punching directions of the pin, whereby
structural flaws or leakage paths are avoided.
It is further advantageous if a section of the pin is shaped to be
round after the at least partial detachment, in particular, the
region of the shaft extending along the longitudinal direction of
the pin which is installed in the feedthrough and by way of which
the pin is inserted into the feedthrough. This is advantageous
since the continuous cut-outs in the feedthrough ceramics are
frequently designed to be round or circular. This results in more
even brazing solder distribution during the liquid phase of the
solder in the gap and in a reduction of brazing solder that is
required. Circular embossing can be implemented by way of a
composite progressive cutting tool, for example. In the flow region
of the solder, the embossing tool is advantageously structured
predominantly perpendicularly to the pin axis so that defined
micro-roughness of at least 2 .mu.m is created. Due to the shaping
of the surface structure of the embossing dies, solder inhibitor
layers from the uppermost layer elements can be embossed into the
pin, which differ in terms of the micro-roughness and surface
structure thereof from the layers located beneath.
In a further preferred exemplary embodiment, the pin is formed on
at least one end section into a gull wing, J-lead or SOP-like shape
after the at least partial detachment. Other shapes from
microelectronics are likewise conceivable. In this way, the contact
surface with the printed circuit board or the adhering amount of
soft solder can be increased and the necessary withdrawal force
between the printed circuit board and the feedthrough can be
increased.
Efficiency during production of a feedthrough can be further
increased by initially detaching only a set of multiple pins that
are connected to a connecting web from the semi-finished product,
wherein preferably the pins of the set are partially detached from
each other. The pins of this set can subsequently be coated and/or
formed together, as described above, and be attached together in
the feedthrough by way of high-temperature brazing, wherein each
pin is disposed in a separate cut-out. The connecting web protects
the pins during transport from deformation and ensures uniform
evenness during assembly across all the pins of the connecting web.
After joining in the assembly, the pins are preferably separated
from each other by removing the connecting web. For this purpose, a
predetermined breaking point can be introduced in one end section
of a pin, preferably next to the connecting web, in a preferred
exemplary embodiment of the method according to the present
invention. This can be implemented by introducing a notch or a
continuous cut-out in this region. As an alternative, the jointly
assembled pins can be shortened to the same height by an individual
cutting process. For this purpose, the feedthrough is clamped on
the flange and on the connecting web and is subsequently detached
simultaneously across all pins.
At least the above object is further achieved by a method for
producing a feedthrough for an electromedical implant, wherein a
body of a feedthrough having at least one continuous cut-out is
provided, moreover the above-described steps for producing a pin
are carried out, and the additional step is carried out, according
to which the pin, or each pin of the set of multiple pins, is
connected to the inner surface of a continuous cut-out of the body
by way of brazing. This method according to the present invention
has the above-described advantages over the conventional methods.
It is particularly preferred to subsequently separate the multiple
pins of the set from each other, preferably by removing a
connecting web and/or along a predetermined breaking point that was
previously introduced into the pin or a common alignment.
At least the above object is further achieved by a method for
producing an electromedical implant comprising a printed circuit
board and using the above-described steps for producing a
feedthrough, wherein subsequently each pin of the feedthrough is
connected to a terminal of the printed circuit board, preferably by
way of brazing or welding. Thereafter, the printed circuit board is
disposed in a housing of the implant, and the feedthrough is
connected to the housing in a hermetically sealed manner.
At least the above object is also achieved by a pin for an
electromedical implant that is produced or producible using an
above-described method.
At least the above object is moreover achieved by a feedthrough for
an electromedical implant that is produced or producible using an
above-described method.
At least the above object is moreover achieved by an electromedical
implant that is produced or producible using an above-mentioned
method.
The method according to the present invention for producing a pin
and a feedthrough and an electromedical implant, and pins and
feedthroughs thus produced, are described hereafter based on
Figures. All features illustrated and/or described form the subject
matter of the present invention, regardless of how they are
combined in the claims or of their dependency reference.
Further features, aspects, objects, advantages, and possible
applications of the present invention will become apparent from a
study of the exemplary embodiments and examples described below, in
combination with the Figures, and the appended claims.
DESCRIPTION OF THE DRAWINGS
In the schematic Figures:
FIG. 1 shows a cross-section through a semi-finished product in the
form of a strip for a pin according to the present invention of a
first exemplary embodiment;
FIG. 2 shows a view from above of a pin according to the present
invention of a second exemplary embodiment after it has been
detached from the semi-finished product;
FIG. 3 shows a perspective view of a further exemplary embodiment
of a pin according to the present invention after it has been
detached from the semi-finished product;
FIGS. 4-17 show further cross-sections through semi-finished
products in the form of a strip for further exemplary embodiments
of pins according to the present invention;
FIG. 18 shows a perspective side view of a further embodiment of a
pin according to the present invention,
FIGS. 19-20 show a view from the side of an end section of a
further exemplary embodiment of a pin according to the present
invention prior to being brazed to the terminal of a printed
circuit board (FIG. 19) and after brazing (FIG. 20);
FIGS. 21-24 show views from the side of end sections of further
exemplary embodiments of a pin according to the present invention
prior to being brazed to the terminal of a printed circuit board
(FIG. 19 and FIG. 21) and after brazing (FIG. 22 and FIG. 24);
FIGS. 25-47 show views from the side of further exemplary
embodiments of pins according to the present invention;
FIGS. 48-51 show views from the side of sections of further
exemplary embodiments of pins according to the present
invention;
FIG. 52 shows a view from above of a section of a semi-finished
product for producing pins according to the present invention,
which illustrates different steps of the production of a pin;
FIGS. 53-55 show views from the side of three exemplary embodiments
of feedthroughs according to the present invention;
FIG. 56 shows a perspective side view of a further exemplary
embodiment of a feedthrough according to the present invention,
FIG. 57 shows a view from above of the exemplary embodiment of a
feedthrough according to the present invention from FIG. 56;
FIG. 58 shows a view from the side onto the exemplary embodiment of
a feedthrough according to the present invention from FIG. 56;
FIG. 59 shows a further view from the side of the exemplary
embodiment of a feedthrough according to the present invention from
FIG. 56; and
FIG. 60 shows a view from above of a section of a semi-finished
product for producing pins according to the present invention,
which illustrates different steps (A to F) of the production of a
pin.
DETAILED DESCRIPTION
Referring to the Figures, in one exemplary embodiment of the method
according to the present invention, a first layer element 1 in the
form of a sheet or strip made of a biocompatible electrically
conducting material (such as, for example, niobium) is initially
cleaned with a solvent (such as, for example, acetone) and
degreased. A second layer element 2 made of a solder (such as, for
example, Au solder) or a soft-solderable material (such as, for
example, nickel) is applied to at least one side of the first layer
element 1. The second layer element (solder layer) 2 is connected
to the first layer element 1, in particular, in a form-locked or
integral manner; for this purpose, it is advantageous if the first
layer element 1 includes a stop or a groove into which the second
layer element 2 can be fitted in a form-locked manner and
positioned in a relative manner on the first layer element 1. The
width of the groove must be at least as large as the second layer
element 2 and the linear expansion caused by thermal expansion. The
second layer element 2 is joined onto the first layer element 1.
This is done by way of brazing, for example. To this end, it is
advantageous to employ a multi-stage brazing process in which first
the second layer element 2 having a higher melting point is joined
onto the first layer element 1. For example, first the nickel layer
element is joined at a temperature of 1100 to 1380.degree. C.
Thereafter, the second layer element 2 made of gold solder is
brazed on at a temperature of 950 to 1090.degree. C.
As an alternative, it is possible to employ other joining methods,
such as, for example, cladding, hot pressure welding, cold roll
bonding or roller seam welding. After every joining step, the
joining region is inspected. For this purpose, for example,
integrated visual inspection, X-ray inspection or thermography is
suited, so as to detect faulty strip regions and eliminate these
from further processing using an automated process. The width of
the strip for the first layer element 1 is preferably at least the
length of the pin to be cut out, plus lateral surfaces that are
used to guide the strip. The guide surfaces of the strip for the
first layer element 1 are preferably provided with openings so as
to allow very precise positioning of the strip in the range of
several hundredths of a millimeter or less. So as to enable
mechanical guidance, it is helpful to provide boreholes, or
clearances or recesses, in the sides of the strip or sheet, which
can be used as centering elements or stops. The strip for the first
layer element 1 is preferably even wider and, more particularly, so
wide that a number of pins can be cut out of the strip. The
thickness of the strip for the first layer element 1 preferably
corresponds to the thickness of the first layer element 1 from
which the pin will later be made, or is slightly thicker or
thinner, so as to compensate for changes in thickness due to
rolling, cladding or hot pressure welding, soldering or roller seam
welding and the like. Comparable considerations apply to the second
layer element 2 and further layer elements, wherein the strips of
the further layer elements are fed without additional lateral
surfaces in the form of a sheet or wire and are applied to the
first layer element 1. A semi-finished product thus produced is
shown in FIG. 1, and in section A of FIG. 60, wherein in the
exemplary embodiment shown in FIG. 1 the top and bottom sides of
the first layer element 1 are provided in each case with a second
layer element 2. The solder layer is thus applied to both sides of
the first layer element 1. Thereafter, a pin is at least partially
detached from the semi-finished product, such as by way of, for
example, punching, chemical milling, laser cutting or water jet
cutting. The width of a section of the semi-finished product thus
detached, as it is also shown in FIGS. 2-3 or in section B of FIG.
60, for example, is approximately 0.1 to 2 mm, and the length is
approximately 0.5 to 50 mm.
FIG. 2 shows a further exemplary embodiment of a pin detached from
a semi-finished product, wherein additionally the flow region or
melting region of the solder 3 (made of niobium, for example) is
illustrated on the first layer element 1 to the right of the second
layer element 2, which preferably represents a solder layer (made
of gold, for example), and an anti-wetting layer element 4 (solder
inhibitor layer) (zirconium oxide) is applied both to the left of
the adhesion layer element 3 and to the right of the second layer
element 2. The surface is adjusted in a targeted manner in the flow
region of the solder 3 by way of, for example, rolling or embossing
so as to improve adhesion between the solder and the third layer
element. It is advantageous to adjust the roughness in the region 3
in a defined manner. It is advantageous in particular to design the
micro-roughness in the solder flow region 60.degree. to 120.degree.
perpendicularly to the pin axis.
The solder layer 2 is made of high-temperature solders such as Au,
AuAg8, AuPt10 or Ti60Ni25Cu15, for example. The anti-wetting layer
element 4 acts as a brazing stop and is made of ceramic layers or
ceramic-containing layers, for example, such as Al2O3, ZrO2, TiO2,
and the like, or graphite or graphite-containing layers, or metals,
or the alloys thereof, which do not have a wetting effect for the
brazing solder of the second layer element 2. After
(high-temperature) brazing, the anti-wetting layer elements 4 can
be removed, for example, by way of brushing, wet cleaning, chemical
etching and the like.
An anti-wetting layer element 4 is also provided in the exemplary
embodiment shown in FIG. 3, however at a distance from each side of
the second layer element 2 (made of Au solder, for example). The
base layer comprising the first layer element 1 is composed of
three electrically conducting layers disposed on top of each other
in this exemplary embodiment, wherein in the region in which a
solder layer is applied to the outside of the electrical conductor,
a second layer element 2 in the form of a solder layer (such as,
for example, Au solder) is also provided on the inside, between two
first layer elements (electrically conducting layers) 1. This has
the advantage that a solder material is also disposed on the
separating edge 5 that is visible from the front.
FIGS. 4-5 show semi-finished products for pins according to the
present invention, which comprise the second layer elements 2 in a
depression of the first layer element 1, so that the first layer
element 1 extends flush with the top side of the electrically
conducting layer. During production, the first layer element 1 is
produced from multiple layers, or a groove of approximately 80% to
120% the depth of the second layer element 2 is provided.
The width of the groove must be at least as large as the second
layer element 2 and the linear expansion caused by thermal
expansion. The second layer element 2 is joined onto the first
layer element 1. This is done by way of brazing, for example. The
solder wets the side walls of the first layer element 1 under a
meniscus. Subsequent processes such as, for example, burnishing,
polishing or grinding can be used to compensate for differences in
height of the solder region and uneven areas from the joining
process.
FIG. 6 shows a semi-finished product in which the material of the
first layer element 1 is sealed with respect to oxidation by way of
a top coat 6 in the form of a polymer layer or an OSP layer. The
material of the top coat 6 is applied to the surface of the first
layer element by way of painting. Immediately before processing,
the top coat 6 can be partially or completely removed, for example,
by way of solvents (such as acetone). As an alternative, the OSP
layer pyrolizes and can be removed thereafter, such as, for
example, by way of brushing, wet cleaning, chemical etching and the
like.
FIG. 7 shows a semi-finished product comprising a first layer
element 1 and, in a recess, comprising two second layer elements
2a, 2b, which include high-temperature solders having different
compositions. For example, the high-temperature solders can differ
with regard to the compositions thereof, and optionally also with
regard to the melting points thereof. The recess is filled by third
layer elements 8 made of ductile material (such as, for example,
aluminum), which ensures better formability during forming, such as
circular embossing, of the pin. The ductile material moreover
prevents the material of the respective second layer element 2a, 2b
from flowing away laterally during circular embossing. It is thus
ensured that the distribution of the respective second layer
element 2a, 2b after forming is homogeneous and even around the
pin.
In the exemplary embodiment shown in FIG. 8, the second layer
element 2 is disposed on an edge of the first layer element 1 so as
to extend flush on one side with the surface of the first layer
element 1. The first layer element 1 is thus profiled by the step
in the region of the surface thereof.
FIG. 9 shows a semi-finished product in which the second layer
element 2 is integrally joined to an edge of the first layer
element 1. This positioning can take place on maximally two sides
of the semi-finished product, as shown. Due to the placement at the
edge, the high-temperature solder of the second layer element 2 is
given a preferred direction during melting. The solder will
distribute predominantly in the plane of the respective second
layer element 2.
In the exemplary embodiment shown in FIG. 10, a top coat 10, which
is applied to the first layer element 1 and to the second layer
element 2 by way of joining, is provided in the region of the
second layer element 2 and of the adjoining first layer element 1.
By profiling of the first layer element 1, disposing the second
layer element 2 directly at the edge of the first layer element 1
and providing the top coat 10, a preferred direction is defined for
the melting or flowing out of the solder of the second layer
element 2 (e.g., from left to right). Contraction due to surface
tension of the solder is prevented by the top coat 10. The solder
is protected from environmental influences (such as, for example,
oxidation, damage, etc.) by the top coat 10 until melting.
FIG. 11 shows an exemplary embodiment in which a first layer
element 1 in the form of a biocompatible, electrically conducting
layer 1 is connected and joined to a second layer element 2
disposed next to the same in the form of a nickel layer as a
soft-solderable material. In this way, an end section of the pin
according to this embodiment is designed as a nickel section and
can thus be brazed well to a contact of a printed circuit board. As
is apparent from FIG. 11, the cross-section of the second layer
element is rectangular.
The exemplary embodiments shown in FIGS. 12-13 illustrate other
shapes of the second layer element 2, the cross-section being
triangular in FIG. 12 and U-shaped in FIG. 13. In particular in the
case of the triangular cross-section, a transition in terms of the
material from the electrically conducting material of the first
layer element 1 to the soft-solderable material of the second layer
element 2 is achieved.
FIG. 14 shows that a diffusion zone 12, in which inter-diffusion of
the materials of the two layer elements 1, 2 takes place, can be
formed between the first layer element 1 and the second layer
element 2 by corresponding procedural steps, such as, for example,
annealing.
In the exemplary embodiments shown in FIGS. 14 and 16-17, a coating
15 is additionally provided, which represents corrosion protection
for the second layer element 2, which frequently comprises Ni, for
example, in the form of a Pd layer. Such a layer can be applied by
way of CVD or PVD, for example.
Instead of the solder layer, the arrangement variants shown in
FIGS. 1, 4-5, 8-9 and 10 are also conceivable for the arrangement
of a second layer element 2 in the form of a soft-solderable
layer.
FIG. 18 shows an exemplary embodiment of a pin according to the
present invention in which the end section 17, with which the pin
can be placed through the insulator 20 of the feedthrough is
circular-embossed after detachment from the semi-finished product.
The second layer element 2 is located in a circular-embossed
region, so that the solder is able to spread substantially evenly
in the ceramic element. The region opposite the circular-embossed
end section 17 still has the original contour of the starting
material.
FIGS. 19, 21 and 23 show different exemplary embodiments of pins
according to the present invention, the end section 18 of which,
which is to be connected to a terminal of a printed circuit board,
was formed into a predefined shape after detachment from the
semi-finished product. The end section 18 shown in FIG. 19 has a
rounded area in the shape of the segment of a quarter circle,
similarly to what is known as the SOP shape. In FIG. 21, the end
section 18 has what is known as a J-lead shape, and in FIG. 23, it
has what is known as a gull wing shape. As described above, the
arrangement of the soft-solderable material as the second layer
element 2, as is apparent from the Figures, initially takes place
by way of application to a semi-finished product and then
detachment therefrom. The final pin geometry is established by
forming (such as, for example, bending, upsetting, etc.). The
position of the easily soft-solderable materials on the pin can be
influenced by the joining of the materials and by the forming
process. FIGS. 20, 22 and 24 in each case show the state after
which the end section 18 of the respective pin was brazed to a
terminal or pad of the printed circuit board. The printed circuit
board is not shown separately. It is apparent that the easily
soft-solderable material of the second layer element 2 causes good
wetting and adhesion promotion between the pin and the printed
circuit board. The solder cone 25 can thus develop beyond the
second element 2.
It is further advantageous if the semi-finished product is formed
prior to detachment, or if the pin is formed after partial or
complete detachment from the semi-finished product, so that a
protrusion 31 and/or a recess 32 are created. FIGS. 25-31 and 34-46
show different variants of such protrusions 31 or recesses
(cavities) 32. They can be provided at various locations on the
outer side (lateral face) of the pin in the direction of the
longitudinal axis. To this end, a protrusion 31 achieves that the
pin acts as a stop during brazing into the feedthrough, as is shown
in FIGS. 34 and 36, and that the pin holds itself in position
during the brazing process. Moreover, as is shown in FIG. 44, a
protrusion 31 in the end section of a pin can serve as a weld lip.
Multiple protrusions 31 (see FIG. 41) at the end of the pin can
assume the function of a crimp tab or a cooling fin for a
downstream welding process.
A recess 32 can serve as a solder stop and inhibit spreading of the
solder. The protrusion 31 and/or the recess 32 can be designed both
individually, which is to say in the form of individual projections
or troughs, or circumferentially in the form of a protruding web or
notch or depression. A protrusion 31 or a recess 32 is preferably
provided in the region of the first layer element 1; however, these
can also extend into the region of the second layer element. The
protrusion 31 or the notch 32 can have a round, an angular or any
arbitrary (see FIG. 34) cross-section. FIGS. 34, 36 and 43
additionally indicate the position of the insulator 20 in the
feedthrough after the pin has been inserted. It is apparent that
the protrusion 31 holds the pin in position in the body 20 of the
feedthrough. In the embodiment variants shown in FIGS. 36 and 43,
the protrusion 31 was generated with a defined cross-section, so
that the protrusion 31 is suitable for correctly positioning the
body 20 of the feedthrough.
As is shown in FIGS. 44-46, the protrusion 31 and the recess 32 can
also be implemented in the form of a widened area or narrowed area
of the pin.
Moreover, predetermined breaking points can be provided in the form
of continuous cut-outs 33, as is shown in FIGS. 32-33 and 47, which
are intended to prevent the electromedical implant from leaking
when the pin is torn off. The predetermined breaking points are
provided in a section of the pin that is located so far on the
outside, which is to say away from the housing interior, that
hermetic sealing of the housing of the implant continues to be
assured.
Further predetermined breaking points in the form of a continuous
cut-out 33 or a recess 32 are shown in FIGS. 49-51. These are
intended to detach the respective pin from the connecting web
(indicated by the dotted line 35 in FIG. 48). The predetermined
breaking points shown as continuous cut-outs 33 can alternatively
also be implemented as notches.
FIG. 38 shows a pin in the form of a sword having a "hilt"
"crossguard" and "blade" (shaft). The "crossguard-like" recess 32
serves as a support and for alignment in the body 20 of the
feedthrough. The downwardly directed extension 31a of the
protrusion 31 is used for engagement or cradling in the body 20 of
the feedthrough. The "blade region" of the pin is introduced into
the body 20 of the ceramic and is therefore preferably designed to
be round. The connection of the header takes place in the region of
the "hilt", preferably by way of laser welding.
FIG. 52 shows a perforation comb, which is comprised of the
semi-finished product comprising partially detached pins (cut clear
by way of punching, for example). The region of the semi-finished
product located at the top in FIG. 52 forms a connecting web 46.
The pins shown in FIG. 52 are shown by way of example in different
stages of manufacture and with different design options of the
predetermined breaking point, which is implemented by way of
continuous cut-outs 33, for example. The three pins shown on the
left side are shown after partial detachment (punching) from the
semi-finished product. Pins four to eight (counting from the left)
have a shaped area in the region 37 and are shortened after the
forming process, by way of renewed punching, for example. The pin
shown on the farthest right was broken out of the perforation comb
along the predetermined breaking point and thereby completely
detached from the semi-finished product.
FIGS. 53-54 show a pin according to the present invention disposed
in a feedthrough comprising a body 20 made of ceramic material. The
body comprises a circumferential flange 22 for arrangement in the
housing of an implant. The pin is seated in a continuous cut-out in
the form of a borehole 23 in the body 20, wherein the two ends of
the pin protrude from the body 20 in the longitudinal direction. At
the end 18 facing the printed circuit board, the pin comprises a
second layer element 2 in the form of a soft-solderable material,
which facilitates brazing to a terminal of the printed circuit
board.
FIG. 55 shows a feedthrough comprising a set of pins, which are
connected in the end section 19 at the end facing away from the
printed circuit board by way of a connecting web 46. After brazing
the pins in the body 20 of the feedthrough, these are detached from
each other along the separating line 47 (dotted). So as to
implement the connecting web 46, the pins are detached only
partially from the semi-finished product, as is shown in FIG. 52,
so that a region of the semi-finished product remains as the
connecting web 46.
The further exemplary embodiment of a feedthrough according to the
present invention shown in FIGS. 56-59 comprises a flange 22, which
is used to dispose the feedthrough in the electromedical implant,
and cylindrical ceramic bodies 20, into each of which a pin is
brazed. Each pin has a hook-shaped end section 18 at the end facing
the printed circuit board, the end section being designed as a
J-lead. The end section can also be used to orient the pin with
respect to the feedthrough and align it. The pin is later joined
with the printed circuit board at the end section 18. In this
region, as is shown in FIG. 21, the pin comprises a second layer
element, which can be easily wetted with soft solder.
FIG. 60 illustrates the steps of producing a pin according to the
present invention by way of an integrated punching-and-bending
process. Proceeding from the sheet-shaped semi-finished product
(see step A) comprising the sheet-shaped first layer element 1 made
of an electrically conducting material and two second layer
elements 2, which are joined thereto and made of two strips and
which are disposed on the first layer element 1 and include a
solder or a soft-solderable material, the pin is produced in steps
by way of punching or forming. For this purpose, first the contour
of the respective pin is partially detached from the semi-finished
product (for example, cut out by way of punching, see step B), and
thereafter the shaft 48 of the pin is turned into a round shape by
way of forming (see step C). This region is used for insertion into
the insulator of the ceramic and will thus be smaller by
approximately 0.05 to 0.4 mm in terms of the diameter than the
borehole in the insulator so as to achieve a solder gap appropriate
for joining. After circular embossing, the length of the pin must
be readjusted by way of severing (cutting to length, such as, for
example, by way of punching, see step D), since the forming process
results in a change of length in the direction of the pin axis. By
way of bending, the shaft 48 of the pin (downward in FIG. 60) and
the upper end section 49 of the pin comprising the soft-solderable
second layer element 2 are formed to obtain a J-lead (step E).
Finally, the superfluous material of the semi-finished product can
be removed (step F). A connecting web 46 in the form of a belt
connects the finished pins and serves as an assembly aid for
simultaneously positioning multiple components. The belt can be
removed at the predetermined breaking points, which are formed by
way of continuous cut-outs 33 or material tapers.
It will be apparent to those skilled in the art that numerous
modifications and variations of the described examples and
embodiments are possible in light of the above teachings of the
disclosure. The disclosed examples and embodiments are presented
for purposes of illustration only. Other alternate embodiments may
include some or all of the features disclosed herein. Therefore, it
is the intent to cover all such modifications and alternate
embodiments as may come within the true scope of this invention,
which is to be given the full breadth thereof. Additionally, the
disclosure of a range of values is a disclosure of every numerical
value within that range.
LIST OF REFERENCE NUMERALS AND SYMBOLS
1 first layer element 2 second layer element 2a, 2b second layer
element 3 adhesion layer element 4 anti-wetting layer element 5
separating edge 6 top coat 8 third layer element made of ductile
metal 10 coating 12 diffusion zone 15 coating 17 end section of the
pin 18 end section of the pin 19 perforation comb 20 body of the
feedthrough 22 flange 23 borehole 25 solder cone 31 protrusion 31a
extension 32 recess 33 continuous cut-out 35 dotted line (shear
edge) 37 region comprising formed area 46 connecting web 47
separating line 48 shaft of the pin 49 end section of the pin A, B
step in the production of a pin according to the invention C, D
step in the production of a pin according to the invention E, F
step in the production of a pin according to the invention
* * * * *